Model comparison
Devstral Small 2505 vs Mercury 2
Mercury 2 is the stronger model overall, scoring 39.1 to 34.3 on the Noometry Index. Devstral Small 2505 costs 2.5× less per token, which makes it the better buy when Mercury 2's lead doesn't matter for your workload.
Last verified . 2 shared benchmarks.
Mistral AISummary
- They share 2 benchmarks with published results for both. Devstral Small 2505 scores higher in 1 category and Mercury 2 in 1 category; 2 gaps are clear of the uncertainty.
- The widest gap is in coding, where Devstral Small 2505 leads 38.9 to 33.5.
- The biggest single-benchmark swing is SciCode: 28.8% for Devstral Small 2505 and 38.7% for Mercury 2.
- Devstral Small 2505 is cheaper at $0.10 / $0.30 per million input/output tokens, against $0.25 / $0.75 for Mercury 2.
- Devstral Small 2505 has downloadable open weights; the other is API-only.
Side by side
| Devstral Small 2505 | Mercury 2 | |
|---|---|---|
| Provider | Mistral AI | Inception |
| Noometry Index | 34.3 | 39.1 |
| Released | 2025-05-07 | 2026-02-20 |
| Weights | Open | Proprietary |
| Context window | 128K | 128K |
| Max output | 128K | 50K |
| Input $ / M tokens | $0.10 | $0.25 |
| Output $ / M tokens | $0.30 | $0.75 |
| Results tracked | 4 | 17 |
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Category by category
Coding Devstral Small 2505 leads
Devstral Small 2505: 38.9 (#166), Mercury 2: 33.5 (#255)
| Benchmark | Devstral Small 2505 | Mercury 2 |
|---|---|---|
| SciCode | 28.8% | 38.7% |
| SWE-bench Verified (bash only) | 56.4% | — |
| LMArena WebDev | — | 1171 |
| WeirdML | — | 43.2% |
| LMArena Coding | — | 1391 |
| ALE-Bench | — | 785.58 |
Reasoning Mercury 2 leads
Devstral Small 2505: 19.7 (#252), Mercury 2: 23.8 (#170)
| Benchmark | Devstral Small 2505 | Mercury 2 |
|---|---|---|
| CritPt | 0% | 0.8% |
| Kagi LLM Benchmark | 37.7% | — |
| LMArena Hard Prompts | — | 1362 |
Knowledge Not comparable
Devstral Small 2505: —, Mercury 2: 36.2 (#172)
| Benchmark | Devstral Small 2505 | Mercury 2 |
|---|---|---|
| Vectara Hallucination Rate | — | 12.3% |
| LMArena Expert | — | 1358 |
Multilingual Not comparable
Devstral Small 2505: —, Mercury 2: 46.6 (#157)
| Benchmark | Devstral Small 2505 | Mercury 2 |
|---|---|---|
| LMArena Non-English | — | 1331 |
| LMArena Chinese | — | 1417 |
| LMArena Russian | — | 1304 |
Instruction Following Not comparable
Devstral Small 2505: —, Mercury 2: 70.2 (#165)
| Benchmark | Devstral Small 2505 | Mercury 2 |
|---|---|---|
| LMArena Instruction Following | — | 1329 |
Long Context Not comparable
Devstral Small 2505: —, Mercury 2: 40.5 (#154)
| Benchmark | Devstral Small 2505 | Mercury 2 |
|---|---|---|
| LMArena Longer Query | — | 1330 |
Writing & Preference Not comparable
Devstral Small 2505: —, Mercury 2: 53.8 (#155)
| Benchmark | Devstral Small 2505 | Mercury 2 |
|---|---|---|
| LMArena Text | — | 1355 |
| LMArena Creative Writing | — | 1289 |
| LMArena Multi-Turn | — | 1358 |
Frequently asked questions
Is Devstral Small 2505 better than Mercury 2?
Mercury 2 is the stronger model overall, scoring 39.1 to 34.3 on the Noometry Index. Devstral Small 2505 costs 2.5× less per token, which makes it the better buy when Mercury 2's lead doesn't matter for your workload.
Which is cheaper, Devstral Small 2505 or Mercury 2?
Devstral Small 2505 is cheaper. It lists at $0.10 per million input tokens and $0.30 per million output tokens; Mercury 2 lists at $0.25 and $0.75.
Is Devstral Small 2505 or Mercury 2 better for coding?
Devstral Small 2505 scores higher on coding benchmarks: 38.9 versus 33.5 in the Noometry coding category.
Which has the bigger context window?
Both accept 128K tokens.
How many benchmarks do Devstral Small 2505 and Mercury 2 share?
2 benchmarks have published results for both models. Devstral Small 2505 has 4 scored results on Noometry and Mercury 2 has 17.